Remove unneeded throws declaration

* ClassNotFoundException is checked,
* but is not thrown by this method
Merge branch 'remove_unneeded_throws' of github.com:LeekAnarchism/dropwizard into LeekAnarchism-remove_unneeded_throws
Revert file mode change of DataSourceFactory
Add test for handling invalid JDBC driver class in DataSourceFactory
Remove obsolete ClassNotFoundException from DB-related classes
Update docs regarding ClassNotFoundException in DB-related classes
Merge branch 'LeekAnarchism-remove_unneeded_throws'